Multiple sim multiple standby strategy on a ue with carrier aggregation

ABSTRACT

A method of minimizing service degradation caused by other-SIM-occupancy of a DSDS or MSMS UE under carrier aggregation is proposed. A UE performs CC selection from the multiple CCs associated with a first SIM to suffer from other-SIM-occupancy to minimize potential service degradation. In a first option, the UE selects one or more CCs that are relatively harmless from other-SIM-occupancy to share HW resource with CCs associated with other SIMs. In a second option, the UE schedules other-SIM-occupancy on more than one CCs of the first SIM to reduce the frequency and duration of the other-SIM-occupancy affected to each chosen CC of the first SIM.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119 from U.S.Provisional Application No. 62/081,692, entitled “eGemini (EvolvedGemini) inventions,” filed on Nov. 19, 2014, the subject matter of whichis incorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to mobile communicationnetworks, and, more particularly, to multiple SIM multiple standby(MSMS) strategy on a UE with carrier aggregation (CA).

BACKGROUND

Dual-SIM Dual-Standby (DSDS) is a very popular feature in smart phonemarkets today, especially in developing countries such as China andIndia. Many mobile phone users have multiple SIM cards for variouspurposes—having different phone numbers for different uses (e.g., onefor business and one for personal), saving roaming fee, compensatingnon-contiguous network coverage, and sharing one device for multiplefamily members. With DSDS feature, mobile phone users can use singledevice to enjoy multiple SIM services. DSDS UE (User Equipment) cangenerally be categorized into two types. A first type is called SingleTalk, where two baseband modules share the same RF module. Single Talkdevice has low cost and no RF coexistence interference. However, SingleTalk requires complex implementation to support Dual-Standby. SingleTalk only supports one voice call, and requires gap to monitor pagingsignals. A second type is called Dual Talk, where two baseband modulesutilize two individual RF modules. Dual Talk only requires simpleimplementation to support dual standby and can support voice calls overboth SIM cards simultaneously. However, Dual Talk device has high costand RF coexistence interference.

The exponential growth of mobile subscribers and smart phoneapplications require substantial increase of wireless bandwidth. Thelong-term evolution (LTE) system is an improved universal mobiletelecommunication system (UMTS) that provides higher data rate, lowerlatency and improved system capacity. In the LTE system, an evolveduniversal terrestrial radio access network includes a plurality of basestations, referred as evolved Node-Bs (eNBs), communicating with aplurality of mobile stations, referred as user equipment (UE). A UE maycommunicate with a base station or an eNB via the downlink and uplink.The downlink refers to the communication from the base station to theUE. The uplink refers to the communication from the UE to the basestation.

To provide higher peak rate, LTE introduces carrier aggregation (CA) toprovide higher bandwidth capable of supporting the high data rate. Inthe carrier aggregation system, multiple component carriers (CCs) areaggregated and jointly used for transmission to/from a single device. InLTE Rel-10, CA operation defines a number of serving cells, one for eachCC. The functionalities of Radio Resource Control (RRC) connection areonly handled by one cell, defined as the Primary Serving Cell (PCell)served by the Primary component carrier (PCC). One or more SecondaryServing Cells (SCell) are designed to add more bandwidth. The demand forhigher bandwidth may require exploiting further on CA operation toaggregate cells from different base stations to serve a single UE,called inter-eNB carrier aggregation (inter-eNB CA).

To support carrier aggregation in LTE, an UE might have multiple sets ofRF transceivers and baseband or digital signal processor (BB/DSP) formultiple CCs. To support Multiple SIM Multiple Standby (MSMS), an UEmight apply the same hardware (HW) resource (i.e., RF transceiver andBB/DSP) to several CCs that are associated with different SIMs. For afirst SIM1 CC that shares the HW resource with CCs associated withanother SIM2, the LTE transmission on the SIM1 CC might be suspended forperforming activities at CCs associated with SIM2, such as receivingpaging to keep UE in standby state. The time when the HW resource of aCC is occupied by a CC associated with another SIM is called“other-SIM-occupancy”. LTE data transmission in uplink and downlink willbe suspended during other-SIM-occupancy. For a CC sufferingother-SIM-occupancy, the ongoing LTE service on the CC will be affected.The performance of service including MO/MT call, high-speed datatransmission, VoLTE, MBMS, and so on might degrade. The degradationrange of performance depends on the frequency and duration ofother-SIM-occupancy, i.e., how frequently other-SIM-occupancy ispresented and how long each other-SIM-occupancy takes.

Typically, eNB is not aware that the phenomenon of other-SIM-occupancyresults from UE's intention of MSMS. If other-SIM-occupancy takes placetoo frequently or keeps up for a long time, a sensitive eNB might thinkthe UE is under severe channel condition. In this case, eNB mightperform several mechanism such as lower down the resource for UE, adjustthe transmit power and timing of UE, or take other actions that areharmful to UE. This problem may become more serious because more andmore smart handheld devices (e.g. smart phone) will be equipped withmultiple radio transceivers and possibly support multiple SIM cards withshared RF resources.

SUMMARY

A method of minimizing service degradation caused by other-SIM-occupancyof a DSDS or MSMS UE under carrier aggregation is proposed. A UEperforms CC selection from the multiple CCs associated with a first SIMto suffer from other-SIM-occupancy to minimize potential servicedegradation. In a first option, the UE selects one or more CCs that arerelatively harmless from other-SIM-occupancy to share HW resource withCCs associated with other SIMs. In a second option, the UE schedulesother-SIM-occupancy on more than one CCs of the first SIM to reduce thefrequency and duration of the other-SIM-occupancy affected to eachchosen CC of the first SIM.

In a first embodiment, a UE establishes a data connection under carrieraggregation in a mobile communications network. The UE is equipped witha first subscriber identity module (SIM) card and a second SIM card. TheUE performs ongoing data communication over multiple component carriers(CCs) associated with the first SIM using a set of RF hardwareresources. The UE selects a CC having the lowest priority based on alist of factors. The UE monitors incoming activities from the second SIMcard over the selected CC with a predefined frequency and a predefinedduration using the same set of RF hardware resources.

In a second embodiment, a UE establishes a data connection under carrieraggregation in a mobile communications network. The UE is equipped witha first subscriber identity module (SIM) card and a second SIM card. TheUE performs ongoing data communication over multiple component carriers(CCs) associated with the first SIM using a set of RF hardwareresources. The UE selects multiple CCs in accordance with apredetermined rule. The UE monitors incoming activities from the secondSIM card over the multiple CCs, each CC monitors with a predefinedfrequency and a predefined duration using the same set of RF hardwareresources.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user equipment (UE) having dual SIM dual standby(DSDS) or multiple SIM multiple standby (MSMS) feature under carrieraggregation in accordance with one novel aspect.

FIG. 2 is a simplified block diagram of a UE having DSDS feature undercarrier aggregation in accordance with one novel aspect.

FIG. 3 illustrates an example of different options of a DSDS UE undercarrier aggregation to minimize service degradation caused byother-SIM-occupancy.

FIG. 4 illustrates one embodiment of a DSDS UE under carrier aggregationprioritizing each of the component carriers of one SIM for sufferingother-SIM-occupancy.

FIG. 5 illustrates another embodiment of a DSDS UE under carrieraggregation distributing multiple component carriers associated with oneSIM for suffering other-SIM-occupancy.

FIG. 6 is a flow chart of one method of minimizing service degradationcaused by other-SIM-occupancy of a DSDS or MSMS UE under carrieraggregation in accordance with one novel aspect.

FIG. 7 is a flow chart of another method of minimizing servicedegradation caused by other-SIM-occupancy of a DSDS or MSMS UE undercarrier aggregation in accordance with one novel aspect.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 illustrates a user equipment (UE) 101 having dual SIM dualstandby (DSDS) or multiple SIM multiple standby (MSMS) feature undercarrier aggregation (CA) in a mobile communication system 100 inaccordance with one novel aspect. Mobile communication system 100comprises UE 101 and a first network #1 and a second network #2. UE 101supports DSDS feature such that multiple SIM cards can be used to accessmultiple networks, e.g., SIM1 is used to access network #1 and SIM2 isused to access network #2. In the example of FIG. 1, UE 101 is a SingleTalk UE with DSDS feature, where two baseband modules share the same RFmodule. Single Talk device has low cost and no RF coexistenceinterference. However, Single Talk requires complex implementation tosupport Dual-Standby. Single Talk UE only supports one voice call, andrequires gap to monitor paging signals. In the example of FIG. 1, UE 101also supports carrier aggregation, where multiple component carriers(CCs), e.g., CC#1 and CC#2, are aggregated and jointly used fortransmission to/from a single device.

As illustrated in FIG. 1, UE 101 establishes an active data connectionunder carrier aggregation with Network #1 registered by SIM1. UE 101transmits and/or receives ongoing data traffic over multiple componentcarriers CC#1 and CC#2 of the data connection. In addition, UE 101 alsomonitors paging signals or system information over Network #2 registeredby SIM2 over a specific component carrier. UE 101 applies the same HWresource (i.e., RF transceiver and BB/DSP) to the multiple CCsassociated with different SIMs. This creates several problems. Network#1 does not know UE 101 needs to monitor the paging or systeminformation over Network #2. The eNodeB radio resource control (e.g.,link adaptation) algorithms in Network #1 may be sensitive to theunexpected gaps and take proactive actions.

The time when the HW resource of a CC is occupied by a CC associatedwith another SIM is called “other-SIM-occupancy”. LTE data transmissionin uplink and downlink will be suspended during other-SIM-occupancy. Fora CC suffering other-SIM-occupancy, the ongoing LTE service on the CCwill be affected. The performance of service including MO/MT call,high-speed data transmission, VoLTE, MBMS, and so on might degrade. Thedegradation range of performance depends on the frequency and durationof other-SIM-occupancy, i.e., how frequently other-SIM-occupancy ispresented and how long each other-SIM-occupancy takes. Typically, eNB isnot aware that the phenomenon of other-SIM-occupancy results from UE'sintention of MSMS. If other-SIM-occupancy takes place too frequently orkeeps up for a long time, a sensitive eNB might think the UE is undersevere channel condition. In this case, eNB might perform severalmechanism such as lower down the resource for UE, adjust the transmitpower and timing of UE, or take other actions that are harmful to UE.

In one novel aspect, UE 101 performs CC selection from the multiple CCsassociated with SIM1 to suffer from other-SIM-occupancy to minimizepotential service degradation. In a first option, UE 101 selects one ormore SIM1 CCs that are relatively harmless from other-SIM-occupancy toshare HW resource with CCs associated with other SIMs. In a secondoption, UE 101 schedules other-SIM-occupancy on more than one SIM1 CCsto reduce the frequency and duration of the other-SIM-occupancy affectedto each chosen SIM1 CC.

FIG. 2 is a simplified block diagram of a UE 201 having DSDS featureunder carrier aggregation in accordance with one novel aspect. UE 201comprises two RF transceivers and BB/DSP modules 207 and 208 and aduplexer/switch 209 coupled with multiple antennas 210, receives RFsignals from antenna 210, converts them to baseband signals, and sendsthem to processor 202. RF and BB/DSP modules also convert receivedbaseband signals from processor 202, convert them to RF signals, andsend out to antenna 210 via duplexer/switch 209. Processor 202 processesthe received baseband signals and invokes different functional modulesto perform features in the UE. Memory 203 stores program instructionsand data 204 to control the operations of the UE. UE 201 comprises twoSIM cards, SIM1 and SIM2. UE 201 supports carrier aggregation, whereCC#1 and CC#2 associated with SIM1 are coupled to their corresponding RFand BB/DSP modules respectively in active state. UE 201 also supportsDSDS feature, where an RF and BB/DSP module might be shared with bothSIM1 and SIM2 to keep SIM2 in standby state while SIM1 is in activestate.

FIG. 2 further illustrates different functional modules in the UE thatcarry out embodiments of the current invention. The functional modulescomprises circuits that may be implemented and configured by hardware,firmware, software, and any combination thereof. For example, UE 201comprises a RRC configuration module 211 manages radio resource control(RRC) layer configuration and RRC connection establishment, a carrieraggregation module 212 manages carrier aggregation functionalities forboth PCC and SCCs including SCC addition and deletion, and a CC selector213 that prioritizes multiple CCs under carrier aggregation and selectsone or more CCs that are relatively harmless from other-SIM-occupancy toshare HW resource with CCs associated with other SIMs. Furthermore, theCC selector may schedule other-SIM-occupancy on more than one CCs toreduce the frequency and duration of the other-SIM-occupancy affected toeach chosen CC.

FIG. 3 illustrates an example of different options of a DSDS UE undercarrier aggregation to minimize service degradation caused byother-SIM-occupancy. In step 311, UE 301 establishes data connectionunder carrier aggregation with a first network #1 through a first SIM1.In step 312, UE 301 starts ongoing data transmission with network #1over multiple CCs through SIM1. In a first option, in step 321, UE 301determines one or more CCs that are relatively harmless fromother-SIM-occupancy to share HW resource with CCs associated with otherSIMs. For example, CC#1 is determined to suffer less harm fromother-SIM-occupancy. In step 322, UE 301 receives paging from a secondnetwork #2 over the determined CC#1. In step 323, UE 301 continues toreceive paging from network #2 over CC#1. Later on, the CC configurationunder CA may have changed, or other network conditions may have changed.Additional CCs may have been added, or some CCs may have been deleted.In step 331, UE 301 detects such change and re-determines one or moreCCs that are relatively harmless from other-SIM-occupancy to share HWresource with CCs associated with other SIMs. For example, CC#2 is nowdetermined to suffer less harm from other-SIM-occupancy. In step 332, UE301 receives paging from a second network #2 over the determined CC#2.In step 333, UE 301 continues to receive paging from network #2 overCC#2.

In an alternative embodiment, in a second option, in step 341, UE 301determines more than one CCs to be scheduled for other-SIM-occupancy, toreduce the frequency and duration of the other-SIM-occupancy affected toeach chosen CC. For example, both CC#1 and CC#2 are selected based on apredetermined rule. In step 342, UE 301 receives paging from a secondnetwork #2 over the determined CC#1. In step 343, UE 301 continues toreceive paging from network #2 over CC#2. Note that the two options canbe combined together. For example, if there are total four CCs, then theUE can select two of the lower priority CCs and scheduleother-SIM-occupancy on both lower priority CCs.

FIG. 4 illustrates one embodiment of a DSDS UE under carrier aggregationprioritizing each of the component carriers of one SIM for sufferingother-SIM-occupancy. In the embodiment of FIG. 4, each of the componentcarriers are assigned to a priority according to a list of factors. Thelist of factors include (but are not limited to): ongoing or potentialservice on that CC; the UE capability on that CC; the bandwidth; duplexsupport; TDD configuration; the allocated resource; whether the CC isprimary or not; whether the CC is associated with master eNB or not; andso on. Typically, a CC that has ongoing MO/MT call, high-speed datatransmission, VoLTE, MBMS has higher priority, a CC has more capabilityhas higher priority, a CC has higher bandwidth has higher priority, a CChas duplex support (both downlink and uplink) has higher priority, a CCwith certain TDD configuration has higher priority, a CC with SPSresource has higher priority, a primary CC has higher priority than asecondary CC, and a CC associated with a master eNB has higher prioritythan a CC associated with a secondary eNB. Generally, CCs with thelowest priority should be considered first to sufferother-SIM-occupancy.

FIG. 4 depicts two examples on how to prioritizing each CC forother-SIM-occupancy purpose. In a first example depicted by table 410,the priority assignment on each CC associated with SIM1 is based oncarrier aggregation. CC#1 is the primary CC, with BW=20 MHz, support FDDmode and DL/UL full duplex. CC#1 is also allocated with SPS resource andhas ongoing VoLTE service. CC#2 is a secondary CC, with BW=20 MHz,support FDD mode and DL/UL full duplex. CC#2 has ongoing MBMS service.CC#3 is a secondary CC, with BW=10 MHz, support FDD mode and DL/UL fullduplex. CC#4 is a secondary CC, with BW=10 MHz, support FDD mode and DLonly. As a result, CC#1 to CC#4 are assigned from higher priority tolower priority respectively. Because CC#4 has the lowest priority amongall CCs, the UE will use CC#4 to perform activities associated withother SIMs.

In a second example depicted by table 420, the priority assignment oneach CC associated with SIM1 is based on dual connectivity. CC#1 is theprimary cell (PCELL) associated with a master eNB. CC#2 is the primarysecondary cell (PSCELL) associated with a secondary eNB. CC#3 is asecondary cell (SCELL) associated with the master eNB. CC#4 is asecondary cell (SCELL) associated with the secondary eNB. As a result,CC#1 to CC#4 are assigned from higher priority to lower priorityrespectively. Because CC#4 has the lowest priority among all CCs, the UEwill use CC#4 to perform activities associated with other SIMs tominimize performance degradation.

FIG. 5 illustrates another embodiment of a DSDS UE under carrieraggregation distributing multiple component carriers associated with oneSIM for suffering other-SIM-occupancy. In the embodiment of FIG. 5, if aUE has multiple SIM1 CCs to choose from, then the UE schedulesother-SIM-occupancy on more than one SIM1 CCs to reduce the frequencyand duration of the other-SIM-occupancy impact on each chosen CC. Forexample, during certain scheduling period, SIM1 CC#i may be scheduled tomonitor paging information from SIM2, as depicted by box 510. In a firstexample, SIM1 CC#i and SIM1 CC#j are both scheduled to monitor paginginformation from SIM2, as depicted by box 520. Under this example, thefrequency of other-SIM-occupancy is reduced by half, while the durationof each other-SIM-occupancy remains the same. In a second example, SIM1CC#i and SIM1 CC#j are both scheduled to monitor paging information fromSIM2, as depicted by box 530. Under this example, the duration ofother-SIM-occupancy is reduced by half, while the frequency ofother-SIM-occupancy remains the same. When multiple CCs are selected,round robin is one way to schedule other-SIM-occupancy. By distributingother-SIM-occupancy over multiple CCs, the impact on each CC is reducedand the overall performance degradation is reduced.

FIG. 6 is a flow chart of one method of minimizing service degradationcaused by other-SIM-occupancy of a DSDS or MSMS UE under carrieraggregation in accordance with one novel aspect. In step 601, a UEestablishes a data connection under carrier aggregation in a mobilecommunications network. The UE is equipped with a first subscriberidentity module (SIM) card and a second SIM card. In step 602, the UEperforms ongoing data communication over multiple component carriers(CCs) associated with the first SIM using a set of RF hardwareresources. In step 603, the UE selects a CC having the lowest prioritybased on a list of factors. In step 604, the UE monitors incomingactivities from the second SIM card over the selected CC with apredefined frequency and a predefined duration.

FIG. 7 is a flow chart of another method of minimizing servicedegradation caused by other-SIM-occupancy of a DSDS or MSMS UE undercarrier aggregation in accordance with one novel aspect. In step 701, aUE establishes a data connection under carrier aggregation in a mobilecommunications network. The UE is equipped with a first subscriberidentity module (SIM) card and a second SIM card. In step 702, the UEperforms ongoing data communication over multiple component carriers(CCs) associated with the first SIM using a set of RF hardwareresources. In step 703, the UE selects multiple CCs in accordance with apredetermined rule. In step 704, the UE monitors incoming activitiesfrom the second SIM card over the multiple CCs, each CC monitors with apredefined frequency and a predefined duration.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. Accordingly, various modifications,adaptations, and combinations of various features of the describedembodiments can be practiced without departing from the scope of theinvention as set forth in the claims.

1. A method, comprising: establishing a data connection under carrieraggregation by a user equipment (UE) in a mobile communication network,wherein the UE is equipped with the first Subscriber Identity Module(SIM) card and a second SIM card; performing ongoing data communicationover multiple component carriers (CCs) associated with the first SIMcard using a set of radio frequency hardware resources; selecting acomponent carrier with the lowest priority based on a list of factors;and monitoring incoming activities from the second SIM card over theselected CC with a predefined frequency and a predefined duration usingthe same set of radio frequency hardware resources.
 2. The method ofclaim 1, wherein a primary CC has a higher priority than a secondary CC.3. The method of claim 1, wherein a CC associated with a master basestation has a higher priority than a CC associated with a secondary basestation.
 4. The method of claim 1, wherein a CC has an ongoing servicehas higher priority than a CC has no ongoing service.
 5. The method ofclaim 1, wherein the list of factors for selecting a CC comprises atleast one of UE capability, a bandwidth, a duplex mode, a time divisionduplex (TDD) configuration, and allocated resource.
 6. The method ofclaim 1, wherein two CCs are selected for monitoring the incomingactivities from the second SIM card with a round robin fashion.
 7. Themethod of claim 6, wherein each CC monitors the incoming activities fromthe second SIM card with a reduced frequency or a reduced duration.
 8. Amethod, comprising: establishing a data connection under carrieraggregation by a user equipment (UE) in a mobile communication network,wherein the UE is equipped with the first Subscriber Identity Module(SIM) card and a second SIM card; performing ongoing data communicationover multiple component carriers (CCs) associated with the first SIMcard using a set of radio frequency hardware resources; selectingmultiple CCs in accordance with a predetermined rule; and monitoringincoming activities from the second SIM card over the multiple selectedCCs, wherein each CC monitors with a predefined frequency and apredefined duration using the same set of radio frequency hardwareresources.
 9. The method of claim 8, wherein the multiple CCs areselected to monitor the incoming activities based on a round robinfashion.
 10. The method of claim 8, wherein if more CCs are selected,then each CC monitors the incoming activities with a reduced frequencyor with a reduced duration.
 11. A user equipment (UE), comprising: afirst Subscriber Identity Module (SIM) card; a second SubscriberIdentity Module (SIM) card; a radio resource control (RRC) module thatestablishes a data connection under carrier aggregation in a mobilecommunication network, wherein the UE performs ongoing datacommunication over multiple component carriers (CCs) associated with thefirst SIM card; a CC selector that selects a component carrier inaccordance with a predetermined rule; and a radio signal transceiverthat monitors incoming activities from the second SIM card over theselected CC with a predefined frequency and a predefined duration. 12.The UE of claim 11, wherein the predetermined rule is for assigningpriorities to each CC based on a list of factors.
 13. The UE of claim12, wherein a primary CC has a higher priority than a secondary CC. 14.The UE of claim 12, wherein a CC associated with a master base stationhas a higher priority than a CC associated with a secondary basestation.
 15. The UE of claim 12, wherein a CC has an ongoing service hashigher priority than a CC has no ongoing service.
 16. The UE of claim12, wherein the list of factors for selecting a CC comprises at leastone of UE capability, a bandwidth, a duplex mode, a time division duplex(TDD) configuration, and allocated resource.
 17. The UE of claim 11,wherein two CCs are selected for monitoring the incoming activities fromthe second SIM card with a round robin fashion.
 18. The UE of claim 17,wherein each CC monitors the incoming activities from the second SIMcard with a reduced frequency or a reduced duration.
 19. The UE of claim11, wherein the predetermined rule is to select multiple CCs to monitorthe incoming activities based on a round robin fashion.
 20. The UE ofclaim 19, wherein if more CCs are selected, then each CC monitors theincoming activities with a reduced frequency or with a reduced duration.